#region Apache License
//
// Licensed to the Apache Software Foundation (ASF) under one or more 
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership. 
// The ASF licenses this file to you under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with 
// the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#endregion

// .NET Compact Framework 1.0 has no support for ASP.NET
// SSCLI 1.0 has no support for ASP.NET
#if !NETCF && !SSCLI && !CLIENT_PROFILE

using log4net.Core;
using log4net.Layout;
using System.Web;

namespace log4net.Appender
{
    /// <summary>
    /// <para>
    /// Appends log events to the ASP.NET <see cref="TraceContext"/> system.
    /// </para>
    /// </summary>
    /// <remarks>
    /// <para>
    /// Diagnostic information and tracing messages that you specify are appended to the output 
    /// of the page that is sent to the requesting browser. Optionally, you can view this information
    /// from a separate trace viewer (Trace.axd) that displays trace information for every page in a 
    /// given application.
    /// </para>
    /// <para>
    /// Trace statements are processed and displayed only when tracing is enabled. You can control 
    /// whether tracing is displayed to a page, to the trace viewer, or both.
    /// </para>
    /// <para>
    /// The logging event is passed to the <see cref="TraceContext.Write(string)"/> or 
    /// <see cref="TraceContext.Warn(string)"/> method depending on the level of the logging event.
    /// The event's logger name is the default value for the category parameter of the Write/Warn method. 
    /// </para>
    /// </remarks>
    /// <author>Nicko Cadell</author>
    /// <author>Gert Driesen</author>
    /// <author>Ron Grabowski</author>
    public class AspNetTraceAppender : AppenderSkeleton
    {
        #region Public Instances Constructors

        /// <summary>
        /// Initializes a new instance of the <see cref="AspNetTraceAppender" /> class.
        /// </summary>
        /// <remarks>
        /// <para>
        /// Default constructor.
        /// </para>
        /// </remarks>
        public AspNetTraceAppender()
        {
        }

        #endregion // Public Instances Constructors

        #region Override implementation of AppenderSkeleton

        /// <summary>
        /// Write the logging event to the ASP.NET trace
        /// </summary>
        /// <param name="loggingEvent">the event to log</param>
        /// <remarks>
        /// <para>
        /// Write the logging event to the ASP.NET trace
        /// <c>HttpContext.Current.Trace</c> 
        /// (<see cref="TraceContext"/>).
        /// </para>
        /// </remarks>
        override protected void Append(LoggingEvent loggingEvent)
        {
            // check if log4net is running in the context of an ASP.NET application
            if (HttpContext.Current != null)
            {
                // check if tracing is enabled for the current context
                if (HttpContext.Current.Trace.IsEnabled)
                {
                    if (loggingEvent.Level >= Level.Warn)
                    {
                        HttpContext.Current.Trace.Warn(m_category.Format(loggingEvent), RenderLoggingEvent(loggingEvent));
                    }
                    else
                    {
                        HttpContext.Current.Trace.Write(m_category.Format(loggingEvent), RenderLoggingEvent(loggingEvent));
                    }
                }
            }
        }

        /// <summary>
        /// This appender requires a <see cref="Layout"/> to be set.
        /// </summary>
        /// <value><c>true</c></value>
        /// <remarks>
        /// <para>
        /// This appender requires a <see cref="Layout"/> to be set.
        /// </para>
        /// </remarks>
        override protected bool RequiresLayout
        {
            get { return true; }
        }

        #endregion // Override implementation of AppenderSkeleton

        #region Public Instance Properties

        /// <summary>
        /// The category parameter sent to the Trace method.
        /// </summary>
        /// <remarks>
        /// <para>
        /// Defaults to %logger which will use the logger name of the current 
        /// <see cref="LoggingEvent"/> as the category parameter.
        /// </para>
        /// <para>
        /// </para> 
        /// </remarks>
        public PatternLayout Category
        {
            get { return m_category; }
            set { m_category = value; }
        }

        #endregion

        #region Private Instance Fields

        /// <summary>
        /// Defaults to %logger
        /// </summary>
        private PatternLayout m_category = new PatternLayout("%logger");

        #endregion
    }
}

#endif // !NETCF && !SSCLI
